Adherence and Long-Acting Injectable Antipsychotics in Schizophrenia: An Update

The effectiveness of any treatment depends on three principal factors: efficacy, adverse effects, and adherence. The first two factors (efficacy and adverse effects) have been the focus of medical reasoning for decades. Adherence has been recently receiving increased attention in the pharmacological treatment of medical conditions such as diabetes and hypertension, as well as psychiatric disorders such as schizophrenia, bipolar disorder, and depression. Nonadherence to antipsychotic treatment is a major problem in the management of schizophrenia. Depending on the ascertainment methods, approximately 40-50% of schizophrenia patients are nonadherent (1,2), and 50-55% of hospital admissions are attributable to nonadherence to medication (1). Guidelines recommend regular adherence monitoring (2), but it is frequently overlooked in overcrowded hospitals and busy outpatient facilities. This is not surprising since most monitoring methods require having sufficient time to talk with the patient and/or his family. The introduction of antipsychotic depot formulations raised hopes that a technological solution to the problem of nonadherence was at hand. Surprisingly, demonstrating the effect of depot formulations on adherence turned out to be less straightforward than expected. In this review, we define nonadherence, examine methods for its assessment, assess causative factors, and appraise its impact on outcomes of schizophrenia. We also review the role of long-acting injectable antipsychotics (LAI), also referred to as ‘depot formulations’. The review is an expanded and updated version of an article that was published in Czech in 2011 (3).